1. Field of the Invention
The present invention relates to a probe card measuring electric characteristics of a semiconductor device (measurement objective) such as an LSI chip.
2. Description of the Related Art
As shown in FIG. 11, a typical conventional probe card basically has a main substrate 1 having an electrode, on an upper surface thereof, connected to an electrode of a measuring instrument, a probe unit 2 arranged so as to be opposite to a lower surface of the main substrate 1 and having a plurality of probes, a contact pin 3 interposed between the main substrate 1 and the probe unit 2 and electrically connecting both, and a reinforcing plate 4 attached to the upper surface of the main substrate 1.
When this probe card is used at high temperature or low temperature, the temperature distribution of the main substrate 1, and the reinforcing plate 4 of the probe card is changed to cause thermal expansion or thermal shrinkage. In other words, the probe card is deformed (warped). The plane of the probe card A is distorted. The deformation due to heat is caused by fixing a plurality of planar members having different thermal expansion coefficients in a face-to-face contact state. In the case of this probe card, the deformation due to heat is caused by the fixed relation between the main substrate 1, and the reinforcing plate 4.
When the probe card is deformed in this way, variations in the height of the probes occur. When using the probe card in such a state to measure a measurement objective, while some probes are brought into contact with some electrodes of the measurement objective, the remaining probes are not brought into contact with the remaining electrodes of the measurement objective. Thus, there is a problem that the probe card A cannot stably measure electric characteristics of a measurement objective in an environment at high temperature or low temperature.